Home Forums Hunting & Shooting Hunter's Campfire Battery tender/trickle charger?

A tender/trickle charger is good for lead acid batteries but you have to keep it on all the time. As mentioned by Walt501 above, an Odyssey (or other good AGM) battery will not self-discharge so much. Also note that AGM batteries are charged with a 40A charger not a <2A charger. When buying a charger, look carefully at the duty cycle because there are a lot of high claims out there "40A" but the fine print tells you it's intermittent and might be as low as 10% duty cycle. The continuous rating might instead be 4A, but the charger will be labeled "200A Start" and "40A Boost" -- it's all smoke. If you study it carefully, you'll see a lot of the high-amp starting claims are actually the current at 3.6V. It's not surprising the current spikes to 100 or 200A because the voltage sags so low when you start cranking -- what a pathetic joke.

Basically, if you want something better than a trickle charger, it's going to take a big-ass transformer and they're usually mounted in a rolling cart and cost several hundred to a thousand dollars or more. Just think what it takes to deliver enough current for welding. Don't try to weld with a little lunchbox size piece of junk, and don't try to charge a big battery with a little wall-wart.

FWIW, like Walt, I've got Odyssey batteries -- my first one was a Sears DieHard Platinum (rebranded Odyssey). I still have it in my big pickup after 11 years. I have about a half dozen of them in vehicles and they're all about 5 to 10 years old and they all work. The ones that don't get used (because they're backup batteries on the 4x4 etc.), I put on the battery cart once a year. I just went down to Napa and bought whatever the biggest battery cart they had was. The AGM prefer a fast charge.

My wife's car is the only one with a lead-acid battery because it's a 2019 and it came from the manufacturer that way. Three months of quarantine and it was dead. Eventually, I'll swap it out because it won't hold a charge, usually after 4 years. I'll put another Odyssey in it. They cost twice as much but last at least 3 times longer and never need a trickle.

Have kept a bunch of old trucks for the past 30 years - sometimes as many as 20 ranging from pickups through fire engine and Mack LTL - and most of them are driven only by me, so they mostly sit.

Almost all use lead/acid batteries and most of those last 12 or 13 years if kept fully charged. Have had success with the Battery Minder (have added wiring to trickle 4 batts per unit) and the cheap units from Harbor Freight have been very dependable - one unit per batt.

I have downsized a bit with the fleet.

Thanks for all the tips and recommendations. Ordered a Battery Tender Plus yesterday, it looks like it will meet my needs well.

Jim, the best one that I’ve used is the Stanley One Touch. Not so much for the charger as that works fine too, but for the accessory DC plug that charges through the cigarette lighter socket. I ordered two more of those DC accessory plugs and cords from Stanley because they can be used on the Battery Tender Plus and the .2 amp tender less expensive Walmart Battery Tender because those two both have the split cord that you can use either the alligator clips or the cigarette lighter socket plug. I never have to lift the hood or worse get to that battery under the back seat. The Battery Tender units only come with the alligator clips, but they do have the split cord and the Stanley DC cigarette cord attachment works great.

Most of them work well.

CTEKs are really nice and will have settings for a variety of types. AGMs require a slightly higher charge voltage, wet batteries, lower. Especially deep cycles.

And no, throwing an AGM in a vehicle with any kind of parasitic drain, which is about everything, for months of stationary sitting, will be even "deader" than a wet battery.
Unhook it and throw a maintainer on it if its setting extended periods.

Low n slow is always preferred, regardless of type.

here ya go

At some small company I designed the nicad battery chargers in the Boeing 767 and years later the 777.

I have friends who designed Lead Acid battery chargers.

They are disgusted with me for letting the batteries in my truck and my car go dead during Covid 19.

I paid for 2 new batteries and a battery charger.

I learned my lesson and now my batteries are ready for the next pandemic.

A few years back, I parked my truck in the garage and went south for the winter. When I came back the battery was completely dead having powered all the security and what ever else that Ford has running through the computer. The last couple years I've had one of those low amp trickle chargers running only a couple hours a day on a timer and that worked well. This year reading the Battery Tender trickle charger instructions, it said that I could leave it connected and it would maintain a full charge in my one year old battery. Okay, since the cars get better mileage and I didn't need 4wd, I parked the truck for a couple of months with that trickle charger plugged in full time. Fast forward to the hunting season and 20 miles down the road my Sync system touch screen goes out. Ford dealer says my Apim is defective and it can't be rebooted. Coincidence maybe, but for the price of a new Apim and Sync display screen installation, I could buy lots of new batteries. I won't be plugging in that trickle charger full time any longer.

I've gone the opposite route on the semi trucks and the farm trucks by installing battery interrupt switches. Anything that gets parked for any length of time gets the switch turned. Yes, you have to reset the clock, but small price to pay compared to dead batteries.

On some of the newer vehicles, the ECM can end up losing IT'S battery charge if not powered for a long time, losing all it's settings. That is a major potential negative.

A flooded lead-acid battery will self-discharge at 4% per week even if you disconnect it. AGM self-discharges at about 1% per month. The flooded lead-acid also has only a 50% Depth of Discharge, whereas AGM can go down 80% DoD. Essentially, the flooded batteries kill themselves faster and they can't go down as far before they're down for the count. The only way to keep a flooded lead-acid battery alive is to keep it on life support all the time. What they're good for is cheap initial cost, repeat sales, and sales of chargers, tricklers, jumper cables, dual-battery isolators, disconnect switches, and booster packs, as well as roadside assistance service subscriptions and tow services. $$$$$

Attached is a link to CTEK battery charger. These chargers are included in most high end vehicle purchases in Europe. Buy a Mercedes and get a smart charger included. A smarter charger needs to be used if you plan on leaving it connected for a while. Most service chargers don't even know if a battery is connected.
https://smartercharger.com/collections/vehicle/products/ctek-multi-us-7002

Keep it out of the weather.